RFR: 8327701: Remove the xlc toolchain [v2]

[Joachim Kern]

On Mon, 11 Mar 2024 08:59:03 GMT, Joachim Kern <jkern at openjdk.org> wrote:

>> make/autoconf/flags-cflags.m4 line 687:
>> 
>>> 685:     PICFLAG="-fPIC"
>>> 686:     PIEFLAG="-fPIE"
>>> 687:   elif test "x$TOOLCHAIN_TYPE" = xclang && test "x$OPENJDK_TARGET_OS" = xaix; then
>> 
>> Just a remark: This code has never been executed, since running with clang on any OS would hit the branch above. Also, the code is syntactically incorrect, missing a trailing `"`.
>
> OK this was a flaw in my introduction of clang toolchain for AIX. The intention was to keep the xlc options in form of their clang counterparts. I will try with a corrected version for clang on AIX and will come back to you.

OK, the `-Wl,-bbigtoc` is not a compiler option but a linker option and it is already set in the linker options.
But the `-fpic -mcmodel=large` should be set to avoid creating a jump to out-of-order code.

So we can replace the

  JVM_PICFLAG="$PICFLAG"
  JDK_PICFLAG="$PICFLAG"


code some lines below by


  if test "x$TOOLCHAIN_TYPE" = xclang && test "x$OPENJDK_TARGET_OS" = xaix; then
    JVM_PICFLAG="-fpic -mcmodel=large"
  else
    JVM_PICFLAG="$PICFLAG"
  fi
  JDK_PICFLAG="$PICFLAG"

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/18172#discussion_r1519747481